Groundnut (Arachis hypogea L.), is an important legume cash crop for the tropical farmers and its seeds contain high amounts of edible oil (43–55%) and protein (25–28%). Even though it is a fairly drought-tolerant, production fluctuates considerably as a result of rainfall variability. To develop a water stress response function in groundnut, research works have been done to improve the performance under varying degrees of stress at various physiological stages of crop growth. This review summarizes recent information on drought resistance characteristics of groundnut with a view toward developing appropriate genetic enhancement strategies for water-limited environments. It is suggested that there are considerable gains to be made in increasing yield and stabilizing the yield in environments characterized by terminal drought stress and by shortening crop duration. Many traits conferring dehydration avoidance and dehydration tolerance are available, but integrated traits, expressing at a high level of organization are suggested to be more useful in crop improvement programs. Possible genetic improvement strategies are outlined, ranging from empirical selection for yield in drought environments to a physiological–genetic approach. It was also suggested that in view of recent advances in understanding drought resistance mechanisms, the later strategy is becoming more feasible. It is summarized that application of knowledge into practice in a systematic manner can lead to significant gains in yield and yield stability of the world’s groundnuts production. Research is needed to develop transferable technology to help farmers of arid and semi-arid regions. Increasing soil moisture storage by soil profile management and nutrient management for quick recovery from drought are some of the areas that need to be explored further.

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Physiological responses of groundnut (Arachis hypogea L.) to drought stress and its amelioration: a critical review

The canopy light extinction coefficient (K) is a key factor in affecting ecosystem carbon, water, and energy processes. However, K is assumed as a constant in most biogeochemical models owing to lack of in-site measurements at diverse terrestrial ecosystems. In this study, by compiling data of K measured at 88 terrestrial ecosystems, we investigated the spatiotemporal variations of this index across main ecosystem types, including grassland, cropland, shrubland, broadleaf forest, and needleleaf forest. Our results indicated that the average K of all biome types during whole growing season was 0.56. However, this value in the peak growing season was 0.49, indicating a certain degree of seasonal variation. In addition, large variations in K exist within and among the plant functional types. Cropland had the highest value of K (0.62), followed by broadleaf forest (0.59), shrubland (0.56), grassland (0.50), and needleleaf forest (0.45). No significant spatial correlation was found between K and the major environmental factors, i.e., mean annual precipitation, mean annual temperature, and leaf area index (LAI). Intra-annually, significant negative correlations between K and seasonal changes in LAI were found in the natural ecosystems. In cropland, however, the temporal relationship was site-specific. The ecosystem type specific values of K and its temporal relationship with LAI observed in this study may contribute to improved modeling of global biogeochemical cycles.

A meta-analysis of the canopy light extinction coefficient in terrestrial ecosystems

Peanut leaf area index, light interception, radiation use efficiency, and harvest index at three sites in Texas

Physiological responses of argentine peanut varieties to water stress.: Light interception, radiation use efficiency and partitioning of assimilates

Shoot and stalk dynamics and the yield of sugarcane crops in tropical and subtropical Queensland, Australia

Four peanut cultivars of Spanish or Virginia botanical type and varying time to maturity were grown at a range of plant densities (44 000 to 352 000 plants ha-1) and spatial arrangements under irrigated conditions in sub-tropical southern Queensland, Australia. Total and pod dry matter production of the very early maturing Spanish cultivar Chico showed strong positive responses to increased plant density up to the highest density tested. Responses were less pronounced for the later maturing Spanish cultivar McCubbin and were minimal for the Virginia cultivars Early Bunch and Mani Pintar. All cultivars were insensitive to spatial arrangements. Accumulation of total dry matter, adjusted for the higher synthesis costs of oil and protein during seed filling, was well correlated to intercepted photosynthetically active radiation (PAR). Much of the variation in dry matter production among cultivars and plant populations could be accounted for by the effects of differing leaf area duration on cumulative intercepted PAR. Radiation use efficiency was negatively associated with the canopy extinction coefficient (k) within most sowing dates, and also negatively associated with minimum temperature across sowing dates for all cultivars except Mani Pintar.Crecimiento y eficacia del use de radiacion en el mani

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0014479700021189

Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. I. Dry Matter Accumulation and Radiation Use Efficiency

The partitioning of dry matter between vegetative and reproductive yield components was analysed for four diverse peanut cultivars at a range of sowing dates and plant populations in sub-tropical Queensland, Australia. Rates of accumulation of pods (pod addition) varied significantly with both cultivar and sowing date. Within cultivars, much of this variation could be attributed to variation in crop growth rate during the critical pod addition period. The proportion of current assimilate distributed to pods depended on inherent cultivar characteristics and also correlated well with the current crop growth rate relative to the crop growth rate during pod addition (that is, with relative source activity). Neither plant density nor spatial arrangement had any significant effects on patterns of assimilate distribution. All cultivars appeared capable of remobilizing stored assimilate to maintain constant rates of pod yield increase despite fluctuations in crop growth rate which might be expected to produce short term source limitations to pod yield accumulation. The harvest index (HI) increased linearly during the entire pod fill period in all cultivars except the very early maturing Spanish cultivar Chico. Neither density nor spatial arrangement affected rate of increase in HI except in Chico, where increased density produced increased rates of increase in HI. Variation in the rate of HI increase among sowing dates was small.Distribution de la materia seca en el mani

G. R. Harch

Papers

Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. I. Dry Matter Accumulation and Radiation Use Efficiency

Environmental and Agronomic Effects on the Growth of Four Peanut Cultivars in a Sub-tropical Environment. II. Dry Matter Partitioning