Chapter 1: Setting Innovation Free in Agriculture

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In Setting Innovation Free in Agriculture from the book Rethinking Food and Agriculture (2020) I offer a comprehensive critique on the current state and future possibilities of agricultural practices, challenging the prevailing scientific, technological, and economic paradigms that have dominated agriculture since the late 19th century.

There and in my research generally, I advocate for a more holistic, sustainable, and innovative approach to food production, recognizing the intrinsic value and interconnectedness of all elements within the agricultural system, while also prioritizing the public good over corporate profits. This includes practical steps like the integration of traditional knowledge, the use of modern technologies for precision agriculture, and the promotion of urban gardening and sustainable waste management practice.

My research at the International Crops Research Institute for the Semi-Arid Tropics in India demonstrates the significant benefits of blending traditional agricultural practices with contemporary scientific insights. By delving into the physiology and yield dynamics of crops like pigeonpea and chickpea, my work emphasizes the critical roles of diversity, resilience, and adaptability in crops—key principles for reshaping agricultural practices towards a sustainable future.

Scientific Papers on Crop Physiology

Effect of harvest methods on the second flush yield of short-duration pigeonpea (Cajanus cajan)

Journal of Agricultural Science (Cambridge University Press, 1987) Vol. 109, 591-593
by Y.S. Chauhan, R. Sheldrake, N. Venkataratnam


Short-duration pigeonpea can give up to three harvests in environments with mild winters (eg. minimum temperature above 10*C) such as those prevailing in peninsular India (Sharma, Saxena & Green, 1978; Chauhan, Venkataratnam & Sheldrake, 1984). This is mainly due to the short time (about 120 days) taken to produce the first flush, and the strong perennial character of pigeonpea. The seed yield of short-duration pigeonpea in this multiple-harvest system may reach 5.2t/ha (Chauhan et al. 1984).

Venkataratnam & Sheldrake (1985) found that the yield of the second harvest of medium-duration pigeonpea was significantly influenced by the method of harvesting of the first flush. The lower the plants were cut, the smaller were the second-harvest yields. A positive relationship between the height at which the stem was cut and success of ratooning was also reported by Suarez & Herreara (1971). Tayo (1985), however, found that in the lowland tropics, plants of a dwarf pigeonpea variety ratooned at 0.3 m had better growth and yield than hand-picked plants; ratooning at 0.6 m height was intermediate. Information on the effect of different harvest methods on yield of short-duration pigeonpea in subtropical, semi-arid environments is not available. The objective of this study was to obtain this information.

Factors affecting growth and yield of short-duration pigeonpea and its potential for multiple harvests

Journal of Agricultural Science (Cambridge University Press, 1987) Vol. 109, 519-529
by Y.S. Chauhan, N. Venkataratnam, R. Sheldrake


Environmental and cultural factors that may limit the yield of short-duration pigeonpea were investigated over three seasons. Plants in the peninsular Indian environment at Patancheru grew less and produced less dry matter by first-flush maturity than at Hisar, a location in northern India where the environment is considered favourable for the growth of short-duration pigeonpea. However, with a similar sowing date in June, the mean seed yields of three genotypes, ICPL4, ICPL81 and ICPL87, were very similar, at about 2-3t/ha, in both environments. This was mainly due to the higher ratio of grain to above-ground dry matter at Patancheru. In addition to the first harvest, all genotypes showed a potential for two more harvests owing to the warm winters at Patancheru. The potential for multiple harvests was particularly high in ICPL 87, which yielded 5.2t/ha from three harvests in 1982-3, 3.6t/ha from two harvests in 1983-4, and 4.1 t/ha from three harvests in 1984-5. The optimum plant population density at Patancheru was 25-35 plants/m2 for ICPL 87, but was higher for the other two genotypes.

At Patancheru, the total dry-matter and seed yield of first and subsequent harvests were significantly reduced by delaying sowing beyond June. Generally, the second-and the third-harvest yields were lower on vertisol than on alfisol under both irrigated and unirrigated conditions.

The total yield of ICPL 87 from two harvests was far higher than that of a well-adapted medium-duration genotype BDN 1, grown over a similar period. The yield advantage was greater on the alfisol because of the better multiple harvest potential of this soil. The results of this study demonstrate that properly managed short-duration genotypes of pigeonpea may have considerable potential for increased yield from multiple harvests in environments where winters are warm enough to merit continued growth.

A Perennial Cropping System From Pigeonpea Grown in Post-Rainy Season

Indian Journal of Agricultural Sciences (1987) Vol. 57, 895-9
by Rupert Sheldrake


The feasibility of growing pigeonpea [Cajanus cajan (LInn.) Millsp.] as a perennial crop was investigated during 1980-82. The medium-duration pigeonpea genotype 'ICP 1-6', sown in the post-rainy season at a population of 30 plants/m2, was allowed to perennate for 18 months, during which it produced 3 flushes of pods at 5,15 and 18 months after sowing. There was a substantial plant mortality after the first-flush harvest, but due to the high-sowing rate many plants survived and regenerated to form a closed canopy in the following rainy season. The mean yield of 2 seasons was 0.5 tonne/ha in the first flush, 1 tonne/ha in the second and 0.05 tonne/ha in the third. The yield from the second flush was obtained without weeding or insecticide spray and was comparable to that of the rainfed crop of medium-duration genotypes. Considerable leaf fall also occurred, which contributed 40kg N/ha to the soil. The yield from the third flush was very low to warrant continuation of the crop for another 3-4 months after the second-flush crop. At this harvest the mean firewood (air-dried stem) yield was 3.5 tonnes/ha. The system has good potential in the wet rainy season fallows in peninsular India, as it enables pigeonpea after the rainy season with little efforts and few inputs.

Second Harvest Yields of Medium Duration Pigeonpeas (Cajanus Cajan) in Peninsular India

Field Crops Research (1985 Dec) Vol. 10, No. 4, 323-332
by N.Venkataratnam and R. Sheldrake


In Peninsular India medium duration pigeonpeas (Cajanus cajan) are normally sown soon after the onset of the monsoon, in June or July; they mature around December, when they are usually cut down and removed from the field. However, if they are harvested by ratooning or by picking the pods, the plants go on to produce a second flush of pods, which matures around March. In experiments conducted in four growing seasons at ICRISAT Center, second harvest yields were usually greater for non-ratooned than ratooned plants, and in experiments conducted on Vertisols they were greater for the plants ratooned high up in the plant than for those cut closer to the ground. Second harvest yields of non-ratooned plants without irrigation on Alfisols were on average 66% of the first harvest yields, but on Vertisols only 37%, in spite of the greater water-holding capacity of the latter. On Alfisols second harvest yields were approximately doubled by a single irrigation, but there was less response to irrigation on Vertisols. The poorer second harvest yields on Vertisols may have been due to the damaging effects of soil cracking on the root system of the plants. In non-ratooned plants from which the first and second flushes of pods were harvested together, yields were less than the total yield obtained from non-ratooned plants in two harvests, even though the yield loss, mainly due to pod shattering, was as little as 4% in one year. The taking of second harvests from pigeonpeas grown on Alfisols may have considerable potential as a method of obtaining additional yield for little extra cost.

Pigeonpea Physiology

Chapter 11 of The Physiology of Tropical Field Crops ed. P. H. Goldsworthy and N. M. Fisher, Blackwell, Oxford (1984)

The Anatomy of the Pigeonpea

Research Bulletin (1981) No. 5
International Crop Research Institute for the Semi*Arid Tropics (ICRISAT), Patancheru
by S.S. Bisen and R. Sheldrake


During the 3 years 1974-77 we studied the anatomy of most of the tissues and organs of the pigeonpea and, in the course of this work, have built up a collection of permanent microscope slides. These are retained in the Anatomy Laboratory at ICRISAT as a reference collection and may be consulted by anyone who is interested.

This report contains a brief and preliminary description of pigeonpea anatomy. We have studied the anatomy of several different cultivars; unless otherwise indicated, the following general descriptions apply to all cultivars investigated. We have not noticed any striking qualitative anatomical differences among cultivars; nodoubt quantitative differences exist, but these are difficult to establish with anatomical methods involving very small samples.

Many of the features of the anatomy of the pigeonpea are similar to those of other dicotyledonous plants, described in standard textbooks of anatomy. We have not attempted to duplicate these descriptions. Some aspects of the anatomy of the pigeonpea have been covered in detail by Dr. P. Venkateshwara Rao in his Ph.D. thesis under reference (nodate). A copy of this thesis is available in the ICRISAT library.

Effect of seed-grading on the yields of chickpea and pigeonpea

Indian Journal of Agricultural Science (1981) Vol. 51, 389-393
by R. Sheldrake, N.P. Saxena, A. Narayanan


Larger seeds of chickpea (Cicer arietinum) and pigeonpea (Cajanus cajan) gave rise to larger seedlings than did smaller seeds. When approximately half the cotyledonary reserves from pigeonpea seeds were removed, seedling weight was reduced to about half of the controls, suggesting that seedling growth was related to the reserve material in the seeds. Seed-grading had no significant effect on the yield of either of these crops grown on a Vertisol and on Alfisol in Andhra Pradesh, or on an Entisol in Haryana or in the Lahaul valley of the western Himalayas. Seeds harvested from pigeonpea grown from larger seeds were significantly heavier than those from plants derived from small seeds, probably because of the genetic heterogeneity of the varieties.

Varietal Differences in Seed Size and Seedling Growth of Pigionpea and Chickpea

Indian Journal of Agricultural Science (1981) Vol. 51, 389-393
by A. Narayanan, N.P. Saxena and R. Sheldrake


The influence of seed size on seedling growth of pigeonpea [Cajanus cajan (Linn.) Millsp.] and chickpea (Cicer arietinum Linn.) was investigated to predict probable consequnces of selection for seed size in breeding programmes. Seeds of 20 pigeionpea varieties with 100-seed weights of 4.5 to 22 g and 23 chickpea varieties with 100-seed weights of 5 to 32 g were sown in the field, and the leaf area and dry weight of the seedlings were measured at intervals up to 56 and 30 days respectively. In both species there was a close linear relationship between 100-seed weight and seedling weight (r = 0.77* for 14-day-old pideonpea; r = 0.82** for 16-day-old chickpea). In pigeonpea the relationship was even closer (r = 0.95**) when varieties having 100-seed weights of over 15 g were excluded. With the advancement of growth the closeness of these relationships declined. Large-seeded varieties of these crops produce larger and more vigorous seedlings, which will have an advantage in stand establishment under adverse conditions.

Effects of Pod Exposure on the Yield of Chickpeas

Field Crops Research (1980) Vol. 3, 180-191
by N.P. Saxena and R. Sheldrake


Pod photosynthesis is known to contribute to seed filling in a number of legume crops, and may also be of importance in chickpeas (Cicer arietium L.), which have green pods possessing stomata. Although the pods of chickpeas are borne in the leaf axils, they generally hang below the leaves and are consequently more or less shaded; but a few lines have recently been identified in which the pods are borne above the leaves. This *exposed pod* character could be incorporated into new cultivars by breeding if it were shown to be of advantage. The effect on yield and yield components of exposing pods of normal cultivars was investigated in field experiments at three locations in India: at Hyderabad and Hissar during the winter season, and in the Lahaul valley in the Himalayas during the summer season. A significant effect of pod exposure on yield or yield components was not observed in any of the experiments, except at Hissar where a slight but significant increase in 100-seed weight was noted. The *exposed pod* character is unlikely to be of use in breeding for higher yield potentials.

Iron Chlorosis in Chickpea (Cicer Arietinum L.) Grown on High pH Calcareous Vertisol

Field Crops Research (1980) Vol. 3, 211-214
by N. Saxena and A. Sheldrake


Genotypic differences exist in the sensitivity of cultivars of chickpea to iron deficiency. Sensitive cultivars exhibited typical iron deficiency symptoms when grown on calcareous soils with high pH. FeSO4 sprays (0.5%) corrected deficiency symptoms and increased yields by up to 50% in cultivars inefficient in iron utilization, but gave no increase in cultivars that were efficient.

Physiology of Growth, Development and Yield of Chickpeas in India

ICRISAT Publications (1980) 106-120 ref.25
Proceedings of the International Workshop on Chickpea Improvement, Hyderabad, India, Feb 28 - Mar 2 1979
by R. Sheldrake and N.P. Saxena


Research conducted by ICRISAT at Hissar (representative of N. India) and Hyderabad (representative of peninsular India) on the growth, pod development, yield components, nutrient uptake, source/sink relationships, fertilizer and irrigation response, effects of intercropping, apex removal, row orientation, sowing pattern, plant density and seed size, cv. plasticity and cv. differences in germination, Fe chlorosis, salinity tolerance, heat tolerance and water stress response of chickpea is reviewed.

Growth and Development of Chickpeas under Progressive Moisture Stress

Stress Physiology in Crop Plants (ed. H.Mussell and R.Staples) Wiley, New York, 1979
by R. Sheldrake and N.P. Saxena


Comparisons of Earlier- and Later-formed Pods of Chickpeas (Cicer arietinum)

Annals of Botany (1979) Vol. 43, 467-473
by R. Sheldrake, N.P. Saxena


In chickpeas (Cicer arietinum) flowering and pod development proceed acropetally. In plants grown under normal field conditions at Hyderabad, in peninsular India, and at Hissar in north India, at successively apical nodes of the branches there was a decline in pod number per node, weight per pod, seed number per pod and/or weight per seed. The percentage of nitrogen in the seeds was the same in earlier- and later-formed pods at Hyderabad; at Hissar the later-formed seeds contained a higher percentage. Earlier- and later-formed flowers contained similar numbers of ovules. The decline in seed number and/or weight per seed in the later-formed pods of 28 out of 29 cultivars indicated that pod-filling was limited by the supply of assimilates or other nutrients. By contrast, in one exceptionally small-seeded cultivar there was no decline in the number or weight of seeds in later-formed pods, indicating that yield was limited by 'sink' size.

Comparisons of Earlier- and Later-formed Pods of Pigeonpeas (Cajanus cajan)

Annals of Botany (1979) Vol. 43, 459-466
by R. Sheldrake, A. Narayanan


On branches of indeterminate cultivars of pigeonpea, flowering begins at the basal nodes and proceeds acropetally; in morphologically determinate cultivars, flowering begins on the apical racemes and proceeds basipetally. In cultivars of both types, within the racemes flowering proceeds acropetally. Under normal conditions more pods are set from earlier-formed flowers than from later-formed flowers, many of which are shed. Consequently the earlier-formed pods are found at the more basal nodes of racemes, and in indeterminate cultivars at the more basal nodes on the branches. The average weight of earlier- and later-formed pods, collected from the basal and apical nodes of the racemes or of the branches, was similar; so was the number of seeds per pod, the weight per seed and the nitrogen content of the seeds. This pattern differs from that found in most herbaceous legumes, where later-formed pods are smaller, and indicates that pigeonpeas set fewer pods than they are capable of filling. This behaviour may be related to the intrinsically perennial nature of pigeonpeas. The comparison of the weights of earlier-and later-formed pods could provide a simple screening procedure for identifying plants with an annual nature among existing cultivars or in breeders' lines.

The Effects of Flower Removal on the Seed Yield of Pigeonpeas (Cajanus cajan)

Annals of Applied Biology (1979) Vol. 91, 383-390
by Rupert Sheldrake, A. Narayanan, N. Venkataratnam


In field experiments carried out at Hyderabad, India with early and medium-duration cultivars of Cajanus cajan sown at the normal time, in July, removal of all flowers and young pods for up to 5 wk had little or no effect on final yield. The flowering period of the deflowered plants was extended and their senescence delayed. The plants compensated for the loss of earlier-formed flowers by setting pods from later-formed flowers; there was relatively little effect of the deflowering treatments on the number of seeds per pod or weight per seed. The plants were also able to compensate for the repeated removal of all flowers and young pods from alternate nodes by setting more pods at the other nodes.

The removal of flowers from pigeonpeas grown as a winter crop resulted in yield reductions roughly proportional to the length of the deflowering period, probably because maturation of these plants was delayed and occurred under increasingly unfavourable conditions as the weather became hotter.

Growth, development and nutrient uptake in pigeonpeas (Cajanus cajan)

Journal of Agricultural Science (Cambridge) (1979) Vol. 92, 513-526
by Rupert Sheldrake and A. Narayanan


The growth and development of two early (Pusa ageti and T-21) and three medium- duration (ST-1, ICP-1 and HY-3C) cultivars of pigeonpea (Cajanus cajan) were compared at Hyderabad, India, in 1974 and 1975; in 1976 cv. ICP-1 was studied. The pigeonpeas were grown on a Vertisol and on an Alfisol. The crop growth rate in the first 2 months was low. The maximum rate of 171 kg/ha/day was found in the fourth month of growth of cv.ICP-1 on Alfisol. The early culitvars, one of which (cv. Pusa ageti) was morphologically determinate, and the other (cv. T-21) indeterminate, did not differ in the proportion of dry matter partitioned into seeds. The mean dry weight of the above- ground parts of the medium cultivars on Vertisol in 1975 was 8.45 t/ha, including 2.23 t/ha of fallen plant material. The mean harvest index (ratio of grain dry weight to total plant dry weight) of these cultivars was 0.24 excluding fallen material and 0.17 taking fallen material into account. Starch reserves were present in the stems during the vegetative phase, but disappeared during the reproductive phase. In 1974 the maximum leaf-area index on Vertisol was 3 and on Alfisol 12.7. The net assimilation rate tended to decline throughout the growth period, but in the medium cultivars increased at the end of the reproductive phase, probably because of photosynthesis in pods walls and stems.

In 1974 and 1975 the growth of roots and distribution of nodules in Vertisol was investigated by means of soil cores. Roots extended below 150 cm and root growth continued during the reproductive phase. Most nodules were found within the first 30 cm of soil, but some were found below 120 cm. In cv. T-21, grown in brick chambers 150 cm deep, at the time of harvest about three-quarters of the mass of the roots was found in the first 30 cm, and the shoot:root ratio was around 4:1.

In 1975 the mean uptake of nitrogen by the medium cultivars on Vertisol was 120 kg/ha, including 34 kg/ha in fallen material. In 1976 the uptake of nitrogen by cv. ICP-1 was 89 kg/ha on Vertisol and 79 kg/ha on Alfisol, including 32 and 23 kg/ha respectively in fallen material. Nitrogen uptake continued throughout the growing period. The percentage of nitrogen in stems and leaves declined as the plants developed and there was a net remobilization of nitrogen from these organs. The pattern of uptake and remobilization of phosphorus resembled that of nitrogen. In 1976 the total uptake of phosphorus by cv. ICP-1 on Vertisol was 5.8 kg/ha and on Alfisol 5.0 kg/ha.

The relatively low yields of pigeonpeas result from a restricted partitioning of dry matter into pods, which may be related to the plants' perennial nature.

A Hydrodynamical Model of Pod-Set in Pigeonpea (Cajunus Cajan)

Indian Journal of Plant Physiology (1979) Vol. 22, 137-143
by Rupert Sheldrake


In pigeonpeas (Cajanus cajan), most flowers are shed without setting pods. Pod-set is reduced by shading, defoliation and the presence of already developing pods, probably because of the reduced availability of assimilates or other nutrients. In pigeonpeas, unlike most leguminous crops, the average weight per pod of earlier and later formed pods is the same; this indicates that pod-filling is not limited by nutrient supply. Pod-set seems to be controlled in such a way that fewer pods develop than the plants are capable of filling. These processes can be represented by a simple working model, in which the assimilate supply corresponds to water in a reservoir, the axis of a branch or a raceme to a horizontal tube connected to the reservoir, and pods to containers of limited volume at a lower level; the connecting tubes between the axis and the 'pods' have an ascending limb, shorter than the descending limb to the pods, creating a siphon. 'Pods' can 'set' only when the level of water in the reservoir is higher than the threshold of the siphon; during the filling of earlier-set 'pods', the setting of other 'pods' is inhibited by the reduction of pressure within the axis. This model may provide a crude representation of mass flow within the phloem from sources to sinks; it also illustrates some of the hydrodynamical factors involved in competition among sinks.

Pigeonpea (Cajanus Cajan) as a Winter Crop in Peninsular India

Experimental Agriculture (1979) Vol. 15, 91-95
by Rupert Sheldrake and A. Narayanan


Pigeonpeas (Cajanus cajan) are normally sown in June or July in India, at the beginning of the monsoon, but trials were carried out at Hyderabad by sowing in October or November as a winter crop. The duration of the crop, especially of the *medium* and *late* cultivars, was much reduced. In 1975*76, October-sown pigeonpeas gave yields comparable to those of the normal season but much lower yields were produced by planting in November 1975. *Medium* and *late* cultivars significantly outyielded early ones. Optimum plant populations for winter crops were 3*5 times higher than are normally used in the monsoon. Pigeonpeas at relatively high population densities could have considerable potential as a winter crop in peninsular India.

The Expression and Influence on Yield of the 'Double-Podded' Character in Chickpeas

Field Crops Research (1978) Vol. 1, 243-253
by R. Sheldrake, N.P. Saxena, L. Krishnamurthy


The number and percentage of nodes bearing two pods in 'double-podded' cultivars of chickpeas growth in northern India (at Hissar) and peninsular India (at Hyderabad) were compared. At Hissar 11% of the pod-bearing nodes were double-podded; at Hyderabad 28% were double-podded on early-sown and 49% on late-sown plants. In all cases the number of double-podded nodes per plant was similar, but different numbers of single- podded nodes per plant were formed, depending on the length of the growing season. At Hyderabad the percentage of double-podded nodes was not significantly affected by population-density nor by shading the plants throughout the reproductive phase. Partial defoliation of the plants reduced the percentage of double-podded nodes, as did the removal of all flowers from the plants for the first two to four weeks of the reproductive phase. The conversion of 'double-podded' plants to 'single-podded' plants by cutting off one of the flowers at every double-flowered node had no effect on yield at a location in the Himalayas where the double-podded character was poorly expressed, but at Hyderabad the yield of the 'single-podded' plants was significantly reduced compared with the 'double-podded' controls. The results indicate that the double-podded character can confer an advantage in yield of about 6 to 11% under conditions in which the character is well-expressed.

Some Effects of the Physiological State of Pigeonpeas: on the Incidence of the Wilt Disease

Tropical Grain Legumes Bulletin (1978) Vol. 11, 24-5
by R Sheldrake, A Narayanan, J Kannaiyan
Full Text — unavailable


The symptoms of the pigeonpea wilt (causal fungus: Pusarium udum) generally appear during the reproductive phase, particularly while pod-filling is taking place (Mundkur, 1935).

In an off-season crop planted in December 1974 we observed that while there was a high incidence of wilt during the pod-filling phase of untreated plants, almost all the plants where pod development had been prevented by the removal of flowers remained healthy.

Conversely, we found that the incidence of the disease increased when the plants were defoliated during the reproductive phase. In an experiment carried out on medium- duration cultivars grown during the normal season (planted in June 1975) leaves were removed at the time flowering began, and subsequent defoliations were made as new leaves were produced. Different degrees of defoliation were employed: 33% (one leaf out of three removed), 50% (alternate leaves removed), 67% (two leaves out of three removed), 75% (three leaves out of four) and 100% (all leaves removed). We found that, in general, the incidence of the wilt increased with the severity of defoliation.

A second experiment was carried out on medium-duration plants (56 lines in the breeders' plots) which had been ratooned at the time of the harvest of the first flush of pods. These plants regenerated new branches and entered into a second reproductive phase, during which (on March 1 1976) one row of plants of each line was completely defoliated and another row was left as a control. Two months later the plants were scored for wilt. Of the controls, 16 out of 380 plants (4%) had wilted whereas 174 out of 360 defoliated plants (48%) had wilted.

Defoliation of plants in the ICRISAT patholigists' wilt-sick plot has also been found to lead to an increase in the incidence of the wilt disease.